Chromosome “fusions” in karyotype evolution
Lysák, Martin A. Laboratory of Plant Cytogenomics, Central European Institute of Technology, Masaryk University, Brno, Czech Republic.
- Terminal chromosome translocation
- Nested chromosome insertion
- Centromere inactivation and loss in dicentric “fusion” chromosomes
- Links to Primary Literature
- Additional Readings
The karyotype is the complement of chromosomes characteristic of an individual, species, genus, or other grouping. Eukaryotic organisms vary in their number of chromosomes, from 1 to 600 per haploid genome (the genes that make up a haploid set of chromosomes). Haploid cells contain a single set of chromosomes. This is in contrast to diploid cells, which contain two complete sets of chromosomes. Although the number of chromosomes is usually species-specific, it can increase or decrease in populations or species. The number of chromosomes can increase through polyploidy (whole-genome duplication), that is, duplication of a whole chromosome set (or sets), or by centric fission, that is, centromere breakage, splitting the original chromosome into two chromosomes. The loss or gain of a single chromosome or a few chromosomes, called aneuploidy, can be caused by erroneous separation of chromatids or chromosomes during meiosis or mitosis. (Note that the term chromatid is used to describe either of the two daughter strands of a replicated chromosome; these strands are joined by a single centromere and will separate into individual chromosomes during cell division.)
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